Electronic display with cooling

ABSTRACT

A method for cooling a display assembly includes forcibly circulating gas about an airflow pathway extending within a housing and extending along opposing sides of an image assembly is provided. Ambient air is ingested into the housing through an intake, passed within the housing in a manner which provides thermal interaction with the circulating gas in said airflow pathway, and exhausted from the housing through an exhaust to change a temperature of the circulating gas.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/751,263 filed May 23, 2022; U.S. application Ser. No. 17/751,263 is acontinuation of U.S. application Ser. No. 17/234,237 filed on Apr. 19,2021; U.S. application Ser. No. 17/234,237 is a continuation of U.S.application Ser. No. 16/933,932 filed on Jul. 20, 2020, now U.S. Pat.No. 11,013,142 issued on May 18, 2021; U.S. application Ser. No.16/933,932 is a continuation of U.S. application Ser. No. 16/708,260filed on Dec. 9, 2019, now U.S. Pat. No. 10,721,836 issued on Jul. 21,2020; U.S. application Ser. No. 16/708,260 is a continuation of U.S.application Ser. No. 15/789,331 filed on Oct. 20, 2017, now U.S. Pat.No. 10,506,740 issued on Dec. 10, 2019; U.S. application Ser. No.15/789,331 is a continuation of U.S. application Ser. No. 14/834,034filed on Aug. 24, 2015, now U.S. Pat. No. 9,801,305 issued on Oct. 24,2017; U.S. application Ser. No. 14/834,034 is a continuation of U.S.application Ser. No. 14/050,464 filed on Oct. 10, 2013, now U.S. Pat.No. 9,119,325 issued on Aug. 25, 2015; U.S. application Ser. No.14/050,464 is a continuation of U.S. application Ser. No. 12/641,468filed Dec. 18, 2009, now U.S. Pat. No. 8,654,302 issued on Feb. 18,2014, which is a non-provisional of U.S. application Ser. No. 61/138,736filed Dec. 18, 2008; U.S. application Ser. No. 12/641,468 is acontinuation-in-part of U.S. application Ser. No. 12/411,925 filed Mar.26, 2009, now U.S. Pat. No. 8,854,595 issued on Oct. 7, 2014, which is anon-provisional application of U.S. application Ser. No. 61/039,454filed Mar. 26, 2008; U.S. application Ser. No. 12/641,468 is acontinuation-in-part of U.S. application Ser. No. 12/556,029 filed Sep.9, 2009, now U.S. Pat. No. 8,373,841 issued on Feb. 12, 2013, which is anon-provisional application of U.S. application Ser. No. 61/095,615filed Sep. 9, 2008; U.S. application Ser. No. 12/641,468 is acontinuation-in-part of U.S. application Ser. No. 12/234,307 filed Sep.19, 2008, now U.S. Pat. No. 8,767,165 issued on Jul. 1, 2014, which is anon-provisional application of U.S. application Ser. No. 61/033,064filed Mar. 3, 2008; U.S. application Ser. No. 12/641,468 is acontinuation-in-part of U.S. application Ser. No. 12/234,360 filed Sep.19, 2008, which is a non-provisional application of U.S. applicationSer. No. 61/053,713 filed May 16, 2008; U.S. application Ser. No.12/641,468 is a continuation-in-part of U.S. application Ser. No.12/237,365 filed Sep. 24, 2008, now U.S. Pat. No. 8,879,042 issued Nov.4, 2014, which is a non-provisional application of U.S. application Ser.No. 61/057,599 filed May 30, 2008; U.S. application Ser. No. 12/641,468is a continuation-in-part of U.S. application Ser. No. 12/235,200 filedSep. 22, 2008, which is a non-provisional of U.S. application Ser. No.61/076,126 filed Jun. 26, 2008; U.S. application Ser. No. 12/641,468 isa continuation-in-part of U.S. application Ser. No. 12/620,330 filedNov. 17, 2009, now U.S. Pat. No. 8,274,622 issued Sep. 25, 2012, whichis a non-provisional of U.S. application Ser. No. 61/115,333 filed Nov.17, 2008; U.S. application Ser. No. 12/641,468 is a continuation-in-partof U.S. application Ser. No. 12/556,209 filed Sep. 9, 2009, now U.S.Pat. No. 8,379,182 issued Feb. 19, 2013, which is a non-provisional ofU.S. provisional application No. 61/095,616 filed Sep. 9, 2008; all ofsaid aforementioned applications are hereby incorporated by reference intheir entirety as if fully recited herein.

TECHNICAL FIELD

The exemplary embodiments described herein generally relate to coolingsystems and in particular to cooling systems for electronic displays.

BACKGROUND

Conductive and convective heat transfer systems for electronic displaysgenerally attempt to remove heat from the electronic components in adisplay through the sidewalls of the display. In order to do this, thesystems of the past have relied primarily on fans for moving internalair (or ingested ambient air) within the housing past the components tobe cooled and out of the display. These components are typically powersupplies. In some cases, the heated air is moved into convectivelythermal communication with fins.

While such heat transfer systems have enjoyed a measure of success inthe past, improvements to displays and new display applications requireeven greater cooling capabilities. Electronic displays are now beingused in outdoor environments and other applications where they may beexposed to high ambient temperatures and even direct sunlight. Inparticular, cooling devices for electronic displays of the past havegenerally used convective heat dissipation systems that function to coolonly the rear interior portion of the display. By itself, this is notadequate in many climates, especially when radiative heat transfer fromthe sun through a display window becomes a major factor. In manyapplications and locations 200 Watts or more of power through such adisplay window is common. Furthermore, the market is demanding largerscreen sizes for displays. With increased electronic display screen sizeand corresponding display window size more heat will be generated andmore heat will be transmitted into the displays. Also, when displays areused in outdoor environments the ambient air may contain contaminates(dust, dirt, pollen, water vapor, smoke, etc.) which, if ingested intothe display for cooling the interior can cause damage to the interiorcomponents of the display.

A large fluctuation in temperature is common in the devices of the past.Such temperature fluctuation adversely affects the electronic componentsin these devices; both performance and lifetime may be severelyaffected. Thus, there exists a need for a cooling system for electronicdisplays which are placed within environments having high ambienttemperatures, possibly contaminates present within the ambient air, andeven placed in direct sunlight.

SUMMARY

Exemplary embodiments may comprise two separate flow paths for gasthrough an electronic display. A first flow path may be a closed loopand a second flow path may be an open loop. The closed loop path travelsacross the front surface of the image assembly, continues to the rear ofthe display where it may enter a heat exchanger, finally returning tothe front surface of the image assembly. The open loop path may drawambient gas (ex. ambient air) through the rear of the display (sometimesthrough a heat exchanger, behind an image assembly, or both) and thenexhausts it out of the display housing. A heat exchanger may be used totransfer heat from the circulating gas to the ambient gas. Inalternative embodiments, the ambient gas may also be forced behind theimage assembly (sometimes a backlight), in order to cool the imageassembly and/or backlight assembly (if a backlight is necessary for theparticular type of display being used). A cross-flow heat exchanger maybe used in an exemplary embodiment.

The foregoing and other features and advantages of the exemplaryembodiments will be apparent from the following more detaileddescription of the particular embodiments of the invention, asillustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of an exemplary embodiment will be obtained froma reading of the following detailed description and the accompanyingdrawings wherein identical reference characters refer to identical partsand in which:

FIG. 1 is a rear perspective view of an embodiment where the rear coverof the display has been removed.

FIG. 2A is a perspective section view of another embodiment showing theclosed loop and open loop channels.

FIG. 2B is a perspective section view similar to the view shown in FIG.2A where the rear and side covers have been removed.

FIG. 3 is a perspective section of another embodiment where ambient gasis ingested only into the heat exchanger and not into optionaladditional channels.

FIG. 4 is a perspective section view of an exemplary embodiment where across-flow heat exchanger is used to separate high power and low powerelectrical assemblies.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

FIG. 1 shows the rear of an embodiment for an electronic display 100,where the rear cover for the display housing has been removed in orderto show the internal components. In this embodiment, the fan assemblies102 and 103 for the closed loop may be placed along two opposing edgesof a heat exchanger 101. Preferably, fan assembly 102 is the inlet forthe heat exchanger and fan assembly 103 is the exit for the heatexchanger 101. These assemblies can optionally be reversed however,where fan assembly 103 is the inlet and fan assembly 102 is the exit.Further, both assemblies 102 and 103 are not required. Some embodimentsmay use only one fan assembly for the closed loop. If only one fanassembly is used, it may be preferable to place the fan assembly at theinlet of the heat exchanger 101, so that the circulating gas is ‘pulled’across the front of the image assembly and pushed through the heatexchanger 101. This is not required however; other embodiments may pullthe isolated gas through the heat exchanger 101. Other embodiments maypush the isolated gas across the front of the image assembly. Fanassemblies 104 and 105 for the open loop may be placed along twoopposing edges of the display housing. Again, both assemblies 104 and105 are not required as some embodiments may use only one assembly andmay use the open loop fan assemblies in a push or pull design. Becausethe various fan assemblies described herein can be placed in multipleorientations, when referring to the placement of the various fanassemblies, the terms ‘push’, ‘pull’, ‘force’, and ‘draw’ will be usedinterchangeably and any orientation may be used with the variousembodiments herein.

The circulating gas which is being forced by the closed loop fanassemblies is primarily circulating around the display. For example, thegas travels in a loop where it passes through a channel, contacting thefront surface of the image assembly (see FIGS. 2A-2B) and absorbs heatfrom the image assembly. The circulating gas is then preferably directed(or forced) into the heat exchanger 101 in order to transfer heat fromthe circulating gas to the ambient gas. Afterwards, the circulating gasexits the heat exchanger 101 and may eventually return to the channeland contact the front surface of the image assembly. The circulating gasmay also pass over several electronic components 110 in order to extractheat from these devices as well. The electronic components 110 may beany components or assemblies used to operate the display including, butnot limited to: transformers, circuit boards, resistors, capacitors,batteries, power modules, motors, inductors, illumination devices,wiring and wiring harnesses, lights, thermo-electric devices, andswitches. In some embodiments, the electrical components 110 may alsoinclude heaters, when the display assembly might be used in cold-weatherenvironments.

In order to cool the circulating gas (as well as optionally cooling abacklight assembly or image assembly) ambient gas is ingested into thedisplay housing by the open loop fan assembly 104 and/or 105. Theambient gas may simply be ambient air which is surrounding the display.In some embodiments, the ambient gas may be air conditioned (orotherwise cooled) prior to being drawn into the display. Once theambient gas is ingested into the display, it may be directed (or forced)through the heat exchanger 101 and optionally also across the rearsurface of the backlight assembly or image assembly (see FIGS. 2A-2B).By using the heat exchanger 101, heat may be transferred from thecirculating gas to the ambient gas. The heated ambient gas may then beexpelled out of the display housing.

Although not required, it is preferable that the circulating gas andambient gas do not mix. This may prevent any contaminates and/orparticulate that is present within the ambient gas from harming theinterior of the display. In a preferred embodiment, the heat exchanger101 would be a cross-flow heat exchanger. However, many types of heatexchangers are known and can be used with any of the embodiments herein.The heat exchanger 101 may be a cross-flow, parallel flow, orcounter-flow heat exchanger. In an exemplary embodiment, the heatexchanger 101 would be comprised of a plurality of stacked layers ofthin plates. The plates may have a corrugated, honeycomb, or tubulardesign, where a plurality of channels/pathways/tubes travel down theplate length-wise. The plates may be stacked such that the directions ofthe pathways are alternated with each adjacent plate, so that eachplate's pathways are substantially perpendicular to the pathways of theadjacent plates. Thus, gas may enter the heat exchanger only throughplates whose channels or pathways travel parallel to the path of thegas. Because the plates are alternated, the closed loop and ambientgases may travel in plates which are adjacent to one another and heatmay be transferred between the two gases without mixing the gasesthemselves (if the heat exchanger is adequately sealed, which ispreferable but not required).

In an alternative design, an open channel may be placed in between apair of corrugated, honeycomb, or tubular plates. The open channel maytravel in a direction which is perpendicular to the pathways of theadjacent plates. This open channel may be created by running two stripsof material or tape (esp. very high bond (VHB) tape) between twoopposite edges of the plates in a direction that is perpendicular to thedirection of the pathways in the adjacent plates. Thus, gas entering theheat exchanger in a first direction may travel through the open channel(parallel to the strips or tape). Gas which is entering in a seconddirection (substantially perpendicular to the first direction) wouldtravel through the pathways of the adjacent plates).

Other types of cross-flow heat exchangers could include a plurality oftubes which contain the first gas and travel perpendicular to the pathof the second gas. As the second gas flows over the tubes containing thefirst gas, heat is exchanged between the two gases. Obviously, there aremany types of cross-flow heat exchangers and any type would work withthe embodiments herein.

An exemplary heat exchanger may have plates where the sidewalls have arelatively low thermal resistance so that heat can easily be exchangedbetween the two paths of gas. A number of materials can be used tocreate the heat exchanger. Preferably, the material used should becorrosion resistant, rot resistant, light weight, and inexpensive.Metals are typically used for heat exchangers because of their highthermal conductivity and would work with these embodiments. However, ithas been discovered that plastics and composites can also satisfy thethermal conditions for electronic displays. An exemplary embodimentwould utilize polypropylene as the material for constructing the platesfor the heat exchanger. It has been found that although polypropylenemay seem like a poor thermal conductor, the large amount of surface arearelative to the small material thickness, results in an overall thermalresistance that is very low. Thus, an exemplary heat exchanger would bemade of plastic and would thus produce a display assembly that is thinand lightweight. Specifically, corrugated plastic may be used for eachplate layer.

As mentioned above, both inlet and exit fan assemblies are not requiredfor the embodiments. Alternatively, only a single fan assembly may beused for each loop. Thus, only an inlet fan assembly may be used withthe closed loop and only an exhaust fan assembly may be used with theopen loop. Alternatively, one of the loops may have both inlet and exitfan assemblies while the other loop only has either an inlet or exitassembly.

The gas used in both loops can be any number of gaseous matters. In someembodiments, air may be used as the gas for both loops. Preferably, thegas which travels through the closed loop should be substantially clear,so that when it passes in front of the image assembly it will not affectthe appearance of the image to a viewer. The gas which travels throughthe closed loop would also preferably be substantially free ofcontaminates and/or particulate (ex. dust, dirt, pollen, water vapor,smoke, etc.) in order to prevent an adverse effect on the image qualityand damage to the internal electronic components. It may also bepreferable to keep the gas within the open loop from havingcontaminates. An optional filter may be used to ensure that the air(either in the closed or open loop) stays free of contaminates. However,in an exemplary embodiment the open loop may be designed so thatcontaminates could possibly be present within the ambient gas but thiswill not harm the display. In these embodiments, the heat exchanger (andthe optional path behind the image assembly or backlight) is properlysealed so that any contaminates in the ambient gas would not entersensitive portions of the display. Thus, in these exemplary embodiments,ingesting ambient air for the ambient gas, even if the ambient aircontains contaminates, will not harm the display. This can beparticularly beneficial when the display is used in outdoor environmentsor indoor environments where contaminates are present in the ambientair.

FIG. 2A shows a cross-section of another embodiment of a display 200. Inthis figure, the rear cover 250 and side covers 251 and 252 are shown toillustrate one method for sealing the overall display 200. The imageassembly 220 is shown near the front of the display 200. As discussedabove, the image assembly 220 may comprise any form of electronicassembly for generating an image, including but not limited to: LCD,light emitting diode (LED), organic light emitting diode (OLED), fieldemitting displays (FED), light-emitting polymers (LEP), plasma displays,and any other flat/thin panel displays. The front display surface 221 isplaced in front of the image assembly 220, defining a channel 290through which the circulating gas may flow. The front display surface221 may be any transparent material (glass, plastic, or composite) andmay optionally comprise several layers for polarizing light, reducingglare or reflections, and protecting the internal display components. Inan exemplary embodiment, the front display surface 221 would comprisetwo panes of glass which are laminated together with index-matchingoptical adhesive. Further, a polarizing layer may be attached to one ofthe panes of glass in order to reduce the internal reflections and solarloading on the image assembly 220. It is most preferable that thepolarizing layer be attached to the inner surface of the front displaysurface 221 (the one facing the closed loop channel 290) and alsocontain an anti-reflective (AR) coating. The front display surface maybe a durable display panel as disclosed in co-pending U.S. applicationSer. No. 12/330,041 filed on Dec. 8, 2008, herein incorporated byreference in its entirety.

For the embodiment shown in FIG. 2A, the image assembly 220 may be anLCD stack with a backlight assembly 222. Some backlights may use coldcathode fluorescent lamps (CCFLs) to produce the illumination necessaryfor generating an image. In an exemplary embodiment, the backlightassembly 222 would comprise a printed circuit board (PCB) with aplurality of LEDs (light emitting diodes) on the front surface. Anexemplary embodiment would have a low level of thermal resistancebetween the front surface of the backlight assembly 222 and the rearsurface 223 of the backlight. A metallic PCB may be used for thispurpose. The rear surface 223 of the backlight may contain a thermallyconductive material, such as a metal. Aluminum may be an exemplarymaterial for the rear surface 223. A second surface 224 may be placedbehind the rear surface 223 of the backlight assembly 222. The spacebetween the rear surface 223 of the backlight and the second surface 224may define an additional optional open loop channel 225 through whichambient gas may travel in order to cool the backlight assembly 222 (orimage assembly 220 if no backlight is used).

FIG. 2B shows the same cross section from FIG. 2A with the rear cover250 and side covers 251 and 252 removed and the closed and open loop airflows shown for explanatory purposes. The closed loop fan assembly 202may be used to propel the circulating gas 210 around the closed loop. Afirst open loop fan assembly 203 may be used to draw ambient gas 211through the heat exchanger 201. Optionally, a second open loop fanassembly 204 may be used to draw ambient gas 212 through the additionaloptional channel 225 for cooling the backlight assembly 222 (or imageassembly 220 if no backlight is used). The optional second open loop fanassembly 204 can also be used to exhaust ambient gas which has traveledthrough the heat exchanger 201 and through the channel 225. If a secondopen loop fan assembly 204 is not used (perhaps because the additionaloptional channel 225 is not used), the first open loop fan assembly 203may be used to exhaust the ambient gas 211 that has traveled through theheat exchanger 201.

As noted above, in an exemplary embodiment the ambient gas 211 and 212does not mix with the circulating gas 210. It may be important for theimage quality that the circulating gas remains free of particulate andcontaminates as this gas travels in front of the image assembly 220.Since gas for the open loop may contain various contaminates, apreferable embodiment should be adequately sealed to prevent the gasfrom the two loops from mixing. This is not necessary however, asfilters (either removable or permanent) may be used to minimize theeffect of particulate for both the open and closed loops.

FIG. 3 is a perspective section view of another embodiment of a displayassembly 10 showing inlet 60 and exhaust 65 apertures for the ambientgas 20. The inlet aperture 60 may contain a screen or filter (removableor permanent) to remove any particulate (although this may not benecessary). One or more fans 50 may be positioned so as to draw theambient gas 20 into the inlet aperture 60 and through the heat exchanger201. In this embodiment, the ambient gas 20 is only drawn through theheat exchanger 201 and not through any additional optional channels.This embodiment may be used when the image assembly 80 (or backlightassembly) does not require the additional cooling of an additionalchannel. For example, and not by way of limitation, this embodiment 10may be used when an OLED is used as the image assembly 80. Further, thisembodiment 10 may be used when the LCD backlight is not generating largeamounts of heat because it is not required to be extremely bright(perhaps because it is not used in direct sunlight). Still further, thisembodiment may be used when the ambient gas 20 contains particulate orcontaminates which may damage the display. In these situations, it maybe desirable to limit the exposure of the display to the ambient gas 20.Thus, in these situations it may be desirable to only ingest ambient gas20 into the heat exchanger 201 and not through any additional coolingchannels.

In some embodiments, the ambient gas 20 may be air conditioned (orotherwise cooled) before it is directed into the heat exchanger 201. Afront display surface 221 may be used to create an anterior (front) wallof the channel 290 and/or protect the image assembly 80 from damage. Anexemplary front display surface 221 may be glass. Another embodiment forthe front display surface 221 may be two panes of glass which arelaminated together using optical adhesive. Solar loading (radiative heattransfer from the sun through the front display surface 221 may resultin a heat buildup on the image assembly 80 (ex. OLED or LCD assembly).This heat may be transferred to the circulating gas as it passes throughthe channel between the front display surface 221 and the image assembly80, where this heat may then be transferred to the ambient gas 20 andexpelled from the display. The image assembly could be any one of thefollowing: LCD, plasma display assembly, OLED, light emitting polymer(LEP) assembly, organic electro luminescence (OEL) assembly, LED displayassembly, or any other flat/thin panel electronic display.

FIG. 4 shows another embodiment where a circulating gas 400 is forcedbetween a front display surface 221and an image assembly 80 and thenthrough a heat exchanger 201 in order to remove at least a portion ofthe heat absorbed from the image assembly 80 and front display surface221. Here, the circulating gas 400 may be propelled by a closed loop fanassembly 410. The heat exchanger 201 may accept circulating gas 400 inone direction while accepting ambient gas 310 in a substantiallyperpendicular direction such that heat may transfer between the twogases.

In this embodiment, an optional additional flow of ambient gas 300 isaccepted through the inlet aperture 350 and directed along channel 225in order to cool the rear portion of the image assembly 80 (possibly abacklight). When this optional additional flow of ambient gas 300 isused, it is preferable that the anterior (front) surface 500 of thechannel 225 be thermally conductive and preferably in thermalcommunication with at least a portion of the image assembly 80. In thisarrangement, the ambient gas 300 may also be used to absorb heat fromthe image assembly 80. In some embodiments, the image assembly may be anLCD with an LED backlight. Here, the LED backlight may be in thermalcommunication with surface 500 so that heat can be transferred from theLED backlight to the ambient gas 300. Alternatively, the image assembly80 may be an OLED assembly and the surface 500 may be in thermalcommunication with the OLED assembly. Inlet aperture 350 may accept bothambient gas 310 and 300, or there may be separate inlet apertures foreach flow of gas 310 and 300.

For the embodiment shown in FIG. 4 , a plurality of ribs are shownplaced within channel 225. These ribs may be thermally conductive and inthermal communication with surface 500. Thus, heat from surface 500 maybe distributed throughout the ribs and removed by the ambient gas 300.It has been found, that this arrangement can provide improved coolingabilities for the image assembly 80 and/or backlight (if necessary). Itcan also provide greater structural rigidity to the overall assembly. Ithas been found that some image assemblies (especially LEDs and OLEDs)may have performance properties which vary depending on temperature.Thus, as the temperature of the image assembly increases, the luminance,color temperature, and other optical properties can vary. When ‘hotspots’ are present within a backlight or illumination assembly, thesehot spots can result in irregularities in the resulting image whichmight be visible to the end user. Thus, with some of the embodimentsdescribed herein, the heat which may be generated by the backlightassembly or image assembly can be distributed throughout the ribs andthermally-conductive surfaces to remove hot spots and cool the backlightor image assembly.

The ribs shown in this embodiment contain a hollow rectangularcross-section, but this is not required. Other embodiments may containribs with I-beam cross-sections, hollow square cross-sections, solidrectangular or solid square cross-sections, ‘T’ cross-sections, ‘Z’cross-sections, corrugated or honeycomb cross-section, or anycombination or mixture of these. Metal may be used to produce the ribsin some embodiments.

In other embodiments, additional heat-producing electronic assembliesmay be placed in thermal communication with the ribs so that heat can beremoved from these assemblies as well. In an exemplary embodiment, powermodules may be placed in thermal communication with the ribs so that theheat from the power modules can be distributed throughout the ribs andremoved by the ambient gas 300.

The circulating gas 400 may also pass over electronic assemblies inorder to accept heat from these electronic assemblies. In this exemplaryembodiment, the electronic assemblies have been separated by the heatexchanger 201 into two groups. The first group of electronic assemblies9 may be considered the high power assemblies and may include but arenot limited to: power modules, inductors, transformers, and otherpower-related devices. The second group of electronic assemblies 7 maybe considered the low power assemblies and may include but are notlimited to: timing and control boards, hard drives and other storagedevices, video cards, software drivers, microprocessors, and othercontrol devices. It is known to those skilled in the art that some highpower electronic assemblies can cause electrical interference with otherelectronic assemblies that may be sensitive to electrical interference.Thus, in the exemplary embodiment shown, the heat exchanger 201 is usedto separate the lower power electronic assemblies 7 from the high powerelectronic assemblies 9 to ensure a minimum amount of interferencebetween the two. Further, some high power electronic assemblies 9 areknown to also generate heat. This heat may be transferred to thecirculating gas 400 prior to introducing this gas into the heatexchanger 201. In the exemplary embodiment shown, ambient air can beingested as the ambient gas 310 and there is little risk of damage tothe electrical assemblies 7 and 9 because the ambient gas 310 wouldpreferably never contact these electrical assemblies. However, theelectrical assemblies 7 and 9 will remain cool (as well as clean anddry) because of the cross-flow from the circulating gas 400.

The cooling system described herein may run continuously. However, ifdesired, temperature sensing devices (not shown) may be incorporatedwithin the electronic display to detect when temperatures have reached apredetermined threshold value. In such a case, the various cooling fansmay be selectively engaged when the temperature in the display reaches apredetermined value. Predetermined thresholds may be selected and thesystem may be configured to advantageously keep the display within anacceptable temperature range. Typical thermostat assemblies can be usedto accomplish this task. Thermocouples may be used as the temperaturesensing devices. The speed of the various fan assemblies can also bevaried depending on the temperature within the display.

It should be particularly noted that the spirit and scope of thedisclosed embodiments provides for the cooling of any type of electronicdisplay. By way of example and not by way of limitation, embodiments maybe used in conjunction with any of the following: LCD (all types), lightemitting diode (LED), organic light emitting diode (OLED), fieldemitting display (FED), light emitting polymer (LEP), organic electroluminescence (OEL), plasma displays, and any other type of thin/flatpanel display. Furthermore, embodiments may be used with displays ofother types including those not yet discovered. In particular, it iscontemplated that the system may be well suited for use with large (55inches or more) LED backlit, high definition (1080i or 1080p or greater)liquid crystal displays (LCD). While the embodiments described hereinare well suited for outdoor environments, they may also be appropriatefor indoor applications (e.g., factory/industrial environments, spas,locker rooms, kitchens, bathrooms) where thermal stability of thedisplay may be at risk.

It should also be noted that the variety of open and closed coolingloops that are shown in the figures may be shown in a horizontal orvertical arrangement but it is clearly contemplated that this can bereversed or changed depending on the particular embodiment. Thus, theclosed loop may run horizontally or vertically and in a clock-wise orcounter-clockwise direction. Further, the open loop may also behorizontal or vertical and can run left to right, right to left, and topto bottom, or bottom to top.

Having shown and described various exemplary embodiments, those skilledin the art will realize that many variations and modifications may bemade thereto without departing from the scope of the inventive concept.Additionally, many of the elements indicated above may be altered orreplaced by different elements that will provide a like result and fallwithin the spirit of the inventive concept. It is the intention,therefore, to limit the inventive concept only as indicated by the scopeof the claims.

What is claimed is:
 1. A method for thermally managing a displayassembly comprising the steps of: circulating gas about an airflowpathway extending within a housing along opposing sides of an imageassembly; and ingesting ambient air into said housing through an intake,passing said ingested ambient air within said housing in a manner whichprovides thermal interaction with said circulating gas in said airflowpathway, and exhausting said ingested ambient air from said housingthrough an exhaust in said housing to change a temperature of thecirculating gas.
 2. The method of claim 1 further comprising the stepsof: providing a filter configured to prevent certain contaminants anddust in said ambient air from entering said display assembly.
 3. Themethod of claim 2 wherein: the filter is provided along the airflowpathway.
 4. The method of claim 2 wherein: the filter is provided at theintake.
 5. The method of claim 1 wherein: the airflow pathway encirclesthe image assembly in at least a two-dimensional fashion.
 6. The methodof claim 1 wherein: said ambient air is circulated through a secondairflow pathway which extends within said housing between said intakeand said exhaust and is fluidly separated from said airflow pathway byone or more barriers.
 7. The method of claim 6 wherein: the airflowpathway comprises a rear chamber located behind the image assembly and achannel located between an inner surface of a front display surface anda forward surface of the image assembly.
 8. The method of claim 7wherein: the airflow pathway comprises a heat exchanger located withinthe rear chamber; and said heat exchanger is fluidly connected to saidairflow pathway and separately fluidly connected to said second airflowpathway.
 9. The method of claim 8 further comprising the steps of:placing electronic components for operating the image assembly withinthe rear chamber and outside of the heat exchanger.
 10. The method ofclaim 8 wherein: the second airflow pathway comprises a first subset oflayers of the heat exchanger; and the airflow pathway comprises a secondsubset of layers of the heat exchanger.
 11. The method of claim 10wherein: the heat exchanger is located along a rear surface of the imageassembly.
 12. The method of claim 7 further comprising the steps of:providing a polarizer at an inner surface of the front display surface.13. The method of claim 12 further comprising the steps of: providing asecond polarizer at a forward surface of said image assembly.
 14. Themethod of claim 2 further comprising the steps of: affixing a firstplate to a second plate by way of optical adhesive to form the frontdisplay surface.
 15. The method of claim 1 wherein: said image assemblycomprises an LCD stack and a backlight assembly.
 16. The method of claim1 further comprising the steps of: providing a first set of fans locatedalong the airflow pathway for forcibly circulating said circulating gasalong the airflow pathway when activated; and providing a second set offans within the housing for forcibly ingesting said ambient air throughsaid intake when activated.
 17. A method for thermally managing adisplay assembly comprising the steps of: circulating a flow of gasabout a first airflow pathway extending within a housing, wherein saidfirst airflow pathway extends along opposing sides of an image assembly;and ingesting a flow of ambient air into said housing through an intake,passing said flow of the ambient air through a second airflow pathwayextending within the housing and exhausting said flow of the ambient airfrom said housing through an exhaust in said housing, wherein at least aportion of said first airflow pathway extends alongside at least aportion of said second airflow pathway to facilitate thermal interactionbetween at least said flow of the ambient air in said portion of saidsecond airflow pathway and said flow of the gas in said portion of saidfirst airflow pathway.
 18. The method of claim 17 further comprising thesteps of: providing a filter at said intake to prevent contaminants anddust within said ambient air from entering said first airflow pathwaywhen said flow of the ambient air is ingested.
 19. The method of claim17 further comprising the steps of: providing a multi-layer heatexchanger, wherein a first subset of the layers form part of said firstairflow pathway and a second subset of the layers form part of thesecond airflow pathway such that said flow of the ambient air and saidflow of the gas are fluidly separated within the housing.
 20. A methodfor thermally managing a display assembly comprising the steps of:activating a first set of one or more fans to circulate a flow of gasabout an airflow pathway extending within a housing along opposing sidesof an image assembly to remove heat from said image assembly byabsorption into said flow of the gas; and activating a second set of oneor more fans to ingest ambient air into said housing through an intake,pass the ingested ambient air through a second airflow pathway extendingwithin the housing to place the ingested ambient air adjacent to atleast a portion of said flow of the gas in said airflow pathway to causeheat from said circulating gas to move to said ingested ambient air, andexhaust said ingested ambient air from said housing through an exhaustin said housing to remove the heat from said display assembly.